Fabrication of integrated circuits involves forming large numbers of very small devices on a single wafer. As fabrication technologies improve, the devices become smaller such that more devices can fit within a smaller amount of space. A commonly formed device is a transistor. A transistor generally includes a gate terminal, a source terminal, and a drain terminal. A channel is positioned below the gate and between the source and drain terminals. Based on the signal applied to the gate, electric current is allowed or prevented from flowing through the channel.
As transistors are formed with smaller sizes, the channels of such devices also become smaller. Smaller channels may present a variety of issues, which are often referred to as the short channel effect. For example, a short channel may allow for current to inadvertently flow between the source and the drain based on voltage differential between the source and drain. To avoid this issue, anti-punch-through features can be formed at or near the bottom of a channel. It is desirable to form such anti-punch-through channels in a manner that maximizes their efficiency.